This page covers the 325 mesh count of plain weave wire mesh: the woven specification per ISO 9044 / ASTM E2016, the particle size it retains, the open area it presents to flow, and the neighbouring counts to step to when the separation requires it.
325 Mesh Specification Row (ISO 9044 / ASTM E2016)
| Mesh count | Wire diameter (mm) | Aperture (mm) | Micron rating (u00b5m) | Open area (%) | Weight SS (kg/mu00b2) | Reference standard |
|---|---|---|---|---|---|---|
| 325-Mesh | 0.036 | 0.042 | 42 | 29.1 | 0.22 | ISO 9044 |
325 Mesh to Micron & Aperture
| Openings per inch | 325 |
|---|---|
| Aperture (opening width) | 0.042 mm |
| Micron rating | 42 µm |
| Standard wire diameter | 0.036 mm |
| Open area | 29 % |
Aperture = (25.4 mm ÷ mesh count) − wire diameter. The micron rating equals the aperture in micrometres; actual retention also depends on particle shape and cake formation.
Wire Diameter Options at 325 Mesh
| Option | Wire dia | Aperture | Micron | Open area | Weight (SS) |
|---|---|---|---|---|---|
| Heavy wire | 0.047 mm | 0.031 mm | 31 µm | 16.1 % | 0.37 kg/m² |
| Standard wire | 0.036 mm | 0.042 mm | 42 µm | 29.1 % | 0.22 kg/m² |
| Fine wire | 0.027 mm | 0.051 mm | 51 µm | 42.8 % | 0.12 kg/m² |
Heavier wire adds strength and abrasion life but closes the aperture; finer wire opens the aperture and raises throughput at the cost of durability. Specify mesh count AND wire diameter to fix the aperture unambiguously.
Open Area & Flow at 325 Mesh
The standard 325 mesh weave presents an open area of about 29%. A common design rule is to keep the clean-mesh approach velocity low enough that initial pressure drop is negligible; the mesh then acts as the cake support.
325 Mesh Cloth Weight
Standard 325 mesh stainless cloth weighs approximately 0.22 kg/m² (density 7.93 g/cm³ basis; brass and copper weave roughly 10% heavier, aluminum about one third). Use this figure for roll handling and freight estimation.
Typical Applications for 325 Mesh Plain Weave Wire Mesh
325 mesh plain weave wire mesh is commonly specified for liquid filtration and clarification, extruder screen packs, hydraulic and fuel strainers, pharmaceutical and food sieving, and laboratory test work.
Plain, Twill or Dutch Weave at This Rating?
At this fineness, compare plain weave against twill (heavier wire, more durable) and dutch weave (higher strength, pressure-resistant, nominal rather than absolute rating) before finalizing the specification.
When to Step Up or Down from 325 Mesh
Move to 400 mesh when particles are passing that must be retained; drop back to 250 mesh when the element blinds too quickly or the pressure drop is excessive. In a multi-layer pack, pair this count with a coarser support mesh downstream to carry the pressure load.